2010 Dodge Grand caravan 3.8L (I think) CEL light came on and codes pulled were p0304 p0300 and p3431 , I'm curious as to what's up with the p3431. Looking it up on the typical obd sites say that it's a code for a cylinder deactivation feature. Could this code be related to my misfire?
Yes, that code could well be related to your misfire.
Codes can be thrown as they are related to the fault recorded and, sometimes, odd codes get recorded... I had a manual Golf which threw an automatic gearbox fault code...
Once the fault has been fixed, then related codes, once cleared, will stay cleared.